A hydrocarbon is an organic compound consisting primarily of hydrogen and carbon. The majority of hydrocarbons found on Earth naturally occur in crude oil, natural gas, coal and biomass. Hydrocarbons are a primary energy source for current civilizations. The predominant use of hydrocarbons is as a combustible fuel source. The inherent ability of hydrocarbons to bond to themselves is known as catenation, and allows hydrocarbon to form more complex molecules, such as cyclohexane, and arenes such as benzene. Greenhouse Gases are products which include primarily incomplete combustion of fuel such as oil, natural gas, coal, or wood. For example, emissions from power plants, industrial plants, refineries, transportation vehicles (including ships, trucks, buses, trains, cars, etc.) are major sources of Greenhouse Gases.
Volatile organic compounds (VOCs) are another pollutant resulting from burning hydrocarbon fuels. They are categorized as either methane (CH4) or non-methane (NMVOCs). The aromatic NMVOCs benzene, toluene, and xylene are suspected carcinogens, and may lead to leukemia with prolonged exposure. 1,3-butadiene is another dangerous hydrocarbon often associated with industrial use.